1. Field of the Invention
The present invention relates to a light source unit capable of emitting a pencil of light having high in-plane uniformity and a projector.
2. Description of the Related Art
In these days, data projectors are used on many occasions as an image projection unit which projects images including an image of a screen and a video image of a personal computer, as well as images based on image data which is stored in a memory card on to a screen. In these data projectors, light emitted from a light source is caused to converge to a micromirror display element called a DMD (Digital Micromirror Device) or a liquid crystal panel so that a color image is displayed on a screen.
Conventionally, the mainstream of these projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made various developments on projectors which use, as a light source, a light emitting diode, a laser diode, an organic EL device or a luminescent material.
The applicant of this patent application proposes in JP-A-2012-42964 a light source unit which includes a blue laser emitting device as an excitation light source, a luminescent wheel on which a luminous light emitting area is disposed circumferentially which is formed by laying a green luminescent material on a reflecting surface, and a red light emitting diode and a blue light emitting diode. In this proposal, light emitted from the red light emitting diode constitutes light source light of a range of red wavelengths, light emitted from the blue light emitting diode constitutes a light source light of a range of blue wavelengths, and luminous light emitted from the green luminescent material by using light emitted from the blue light emitting device as excitation light constitutes light source light of a range of green wavelengths.
Although the light source unit uses the blue laser emitting device and the green luminescent material as a green light source, when blue laser light functioning as excitation light is shone on to the luminescent material, unevenness in in-plane uniformity of light is produced in the whole of the pencil of light as excitation light, and therefore, it has been difficult to ensure the in-plain uniformity of luminous light emitted from the luminescent material as well.